Conventional bathtubs are very difficult for handicapped or infirm individuals to climb into or out of. Various devices have been designed to provide a power-assisted lift to raise and lower the individual from the level of the bathtub rim to the bottom of the tub.
For example, U.S. Pat. No. 3,106,723 issued Oct. 15, 1963 to Carpenter discloses a power-elevatable bath tub seat which uses a vertically aligned compressed air cylinder to raise and lower a seat platform. Considerable permanent modification to the existing bathtub is required in this device, as a source of compressed air pressure is required and the power cylinder is installed in a recess in the floor below the tub to extend vertically through the bottom of the tub.
U.S. Pat. No. 3,400,410 issued Sept. 10, 1968 to Sallinger discloses a bathtub device designed to be manufactured of lightweight aluminum frame. The manual rotation of a crank handle is used to raise and lower the seat. This device takes considerable time and energy for an individual to raise or lower by himself or herself.
U.S. Pat. Nos. 4,419,776; 4,557,002 and 4,660,234 all issued to Schmidt disclose various designs for bathtub lifts which utilize the household water pressure to raise the seat platform. These devices use flexible hoses or bellows which fill with water under pressure to force the seat platform upwardly. Such devices have not been found to be sufficiently reliable to achieve commercial success.
There is therefore a need for a bathtub lift which can be readily installed without modifying the bathtub structure, is able to work from the water pressure provided by the household water supply, and which operates effectively to raise and lower the individual in the bathtub.